We recently conducted a daylight simulation study for Apptivity Lab’s new office space in Subang Jaya. Apptivity Labis a software development firm with a focus on producing mobile applications. This project was an interior design collaboration with the interior design firm, In C Studio. Apptivity Lab intents for their new office space to be designed, constructed, and operated in a sustainable manner.
Since this is an interior fit-out project, a few key design specifications are beyond our control. One of which is the window/glazing visible light transmission (VLT). VLT is the total amount of visible light that passes through a glazing. The higher the VLT, the more daylight harvesting opportunity there is. Lower VLT values equates to dark tinted windows and makes a building look dull from within due to the lack of daylight. It is recommended to match your glass VLT value with the daylight harvesting strategy. In general, ideal VLT values are within 35% to 45%. Anything lower than 35% may be too dark, and anything higher than 45% may be too glaring.
The glazing VLT specified for Apptivity Lab’s office is 10%. Which is rather dark and does not let in much natural daylight. A few scenarios were simulated to examine the best daylight harvesting strategy.
Below are results from the analysis. Areas in green show usable daylight (daylight factor within 1% < DF <3.5%)
Case 1: Base Case
Case 2: Horizontal Blinds
Case 3: Light Shelf
Case 4: Light Shelf & Ceiling
Summary of results
Case 1, the Base Case shows the best daylight results. This simulation study shows that conventional daylight harvesting tools like light shelfs are not effective, especially for windows with very low VLT (dark tint). This results are comparable with previous literature by Zakhour, “The Influence of Selected Design Parameters on the Performance of Light Shelves under Overcast Conditions”.
Therefore, if you are moving in to a new space with very dark windows, conventional daylight harvesting tools are not effective. Hence it is recommended to not design additional daylight harvesting features.
Check out related articles like What You Need To Know About Energy Efficiency in Buildings and Daylight Harvesting in Malaysia here.
Author: Ir. Julian Saw
